In the template you are using, you reference the css classes thumb and thumb-wrap. These are not just strings added to the html structure, they have meaning in the CSS on the page. Here are some selected bits according to firebug that apply here:

These rules describe how to style elements with the thumb and thumb-wrap classes when placed inside a container with the images-view id. You have the id set elsewhere in your code, but if you want to remove that, you may be able to simplify these rules.

The float:left; style is specifically what is causing them to line up left-to-right, then top-to-bottom. It is up to you of course what other styling you want to use, but if these rules aren't in a CSS file on your page, those elements won't be styled by them.

In the template you are using, you reference the css classes thumb and thumb-wrap. These are not just strings added to the html structure, they have meaning in the CSS on the page. Here are some selected bits according to firebug that apply here:

These rules describe how to style elements with the thumb and thumb-wrap classes when placed inside a container with the images-view id. You have the id set elsewhere in your code, but if you want to remove that, you may be able to simplify these rules.

The float:left; style is specifically what is causing them to line up left-to-right, then top-to-bottom. It is up to you of course what other styling you want to use, but if these rules aren't in a CSS file on your page, those elements won't be styled by them.

CSS in GWT starts out as the same as CSS in regular html/js applications - make a css file and reference it with a <link> tag, or just stick the style on the html page somewhere in a <style> tag. In these cases, all of the standard rules about css still apply - nothing special for GWT or GXT, any normal documentation should be helpful to learn css.

Beyond that, GWT can also optimize your CSS like it does the rest of your code if you use CssResource and ClientBundle. Documentation for these can be found at https://developers.google.com/web-to...le#CssResource - the basic idea is that you keep the CSS in your code, you write a interface that exposes the compiled names of all of the css classes, and you call those methods (i.e. thumbWrap()) instead of referring to the specific string 'thumb-wrap' - this lets the compiler make all of your css names simpler. GXT 3 makes very heavy use of CssResource, though GXT 2 doesn't use it at all to remain compatible with old versions of GWT. But you don't need to use CssResource in order to use CSS in GWT.